High-protein diets are known to reduce weight and fat deposition. However, there have been only a few studies on the efficacy of different types of
high-protein diets in preventing
obesity. Therefore, the emphasis of this study lies in comparing the efficacy of two
high-protein diets (
milk protein and
whey protein) in preventing
obesity and exploring specific mechanisms. Eighty Sprague Dawley rats were divided into two groups and fed with
milk protein concentrate (MPC) and
whey protein concentrate (WPC) for 12 weeks. Each group was divided into four levels: two low-fat regimens with either low or high
protein content (L-14%, L-40%) and two high-fat regimens with either low or high
protein content (H-14%, H-40%). The studies we have performed showed that rats treated with MPC at the 40%
protein level had significantly reduced
body weight, fat weight and fat ratio gain induced by a high-fat diet, while the
protein level in the WPC group had no effect on
body weight or body fat in rats fed with a high-fat diet. What is more, rats fed with MPC at the H-40% energy level showed a significant decrease in plasma
triglyceride, total
cholesterol and
low-density lipoprotein cholesterol levels and a significant increase in plasma
high-density lipoprotein cholesterol levels compared with the H-14% energy level group. In contrast, in the WPC groups, increasing the
protein content in high-fat diets had no significant influence on plasma
lipid levels. The results of the
amino acid composition of the two
proteins and plasma showed that the MPC diet of 40%
protein level increased the transsulfuration pathway in rats, thereby increasing the level of H2S. This research work has shown that not all types of
high-protein diets can effectively prevent
obesity induced by high-fat diets, as effectiveness depends on the
amino acid composition of the
protein.